The discovery was made by a location scout on the first day of the independent film shoot and production was shut down for two hours as police investigated.

A bomb squad was also called to the scene and experts managed to safely remove the rusty grenade, which was identified as a World War Two-era training device - and not a real explosive, reports

Sister Cities, based on Colette Freedman's play of the same name, also stars Alfred Molina and Michelle Trachtenberg, but they were not on set at the time of the grenade scare, according to

The film, directed by Sean Hanish, is about four estranged sisters who reunite following their mother's alleged death. It is slated for release next year (16).